Current auxiliary systems on an earth moving machine, such as an air conditioner, cooling fans, or pilot pumps, are powered by the engine of the earth moving machine. The auxiliary systems are belt or gear driven systems which are connected to the engine. The auxiliary systems are driven at a speed dictated by the speed of the engine. For example, the speed of the engine can vary between low idle, i.e., 700 rpm, and high idle, i.e., 2400 rpm. The variance in the engine speed is dependent on the particular work function the earth moving machine is performing, as well as the load that the engine is experiencing.
An earth moving machine, such as an excavator, has a transmission system and a hydraulic system, both of which are driven by a drivetrain connected to the engine. The hydraulic system is connected to and drives a work implement, such as a boom, stick, and bucket. The load placed on the engine will vary in large part due to the current load or work function being performed by the work implement. Varying the engine speed to operate the work implement in a desired manner also varies the input power to the auxiliary systems. Therefore, a pilot pump for the hydraulic system, which is sized to provide a required flow at a low idle engine speed of 700 rpm, is forced to operate at engine speeds ranging from 700 rpm to 2400 rpm. The result is wasted power because the auxiliary system can not use all the available power provided by the engine.
The fact that these auxiliary systems are either belt or gear driven also means that they place a continuous load on the engine. If the engine is experiencing a heavy loading condition due to an increased bucket load, for example, there is currently no way to reduce the load of the auxiliary systems. If the load on the engine resulting from the auxiliary systems could be selectively reduced or momentarily eliminated, then more of the available engine power could be applied to operating the work implement when needed.
In addition, the fact that auxiliary systems are currently belt or gear driven restricts the possible placement of these systems on the current earth moving machines. Belt or gear driven systems currently need to be in close proximity to the drivetrain. The placement of the auxiliary systems effects design options when a new machine is being designed.
The present invention is directed toward overcoming one or more of the problems as set forth above.